Composite wood-metal structural member



Feb. 28, 1933. MACOMBER 1,899,344

COMPOSITE WOOD METAL STRUCTURAL MEMBER Filed Dec. 4, 1928 N h w W a 6 1 h i, ii!

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Application filed December 4,1928 Serial No. 323,673.

My invention relates to composite memposite member before they are rigidly secured bers and particularly. to structures of this together;f'f I I i a character intended for use withwoodfioors. I Figures 7, 8, 9 and 10 are transverse verti- Various types of members are shown in the cal sectionsofra floor joist inwhich other accompanying drawing and hereinafter fully types of my improved composite; member '55 described, both for use as transverse struchavebeen incorporated; and, v v tur'al' units as wellas for columns. One prac- Figures 11 and 12 are horizontalsections ticable application of my improved composof columnsin which, two types of my im ite member is for: use as the top chord-of provedcomposite memberam utilized. a 10 a floor joist and in said use the joist contain Referring'to the annexeddrawing in which ing the composite member is intended as a the same parts are indicated by the same resubstitute for wood joists or is used in comspective numbers in the several views, a petition with said woodijoists, the wood coma wooden element such as a, rectangular section ponent of the composite member serving as l is secured to a metal element such as an a nailingstrip to which the wood floors are angle? havingthe horizontal leg 3 and-the directly secured, in addition to carrying a vertical leg 4, Figures 1 to 6, this wood and part of the stresses to which the chordris steel beingrelatively so proportioned that subjected. a I eachwill yield substantially the same amount J o Satisfactory operation of such a composunder a given loading. In other words, if ite member isdependent upon "such a rigid thegm-odulusof elasticity ofthe woodlbe preconnecting together of the. wood and metal sumed to be two million and the modulus of" as will make them work together. One satiselasticity of the metal angle be presumed to, factory way of accomplishing thisresult is be thirty million, then an area of'wood is illustrated by the composite member shown used which is fifteen times as largeas the area in the accompanying drawing and herein- 'of the steel. These members so proportioned a after fully described. a 1 are theniastened together a 'manner to The annexed drawing and the following provide a j ointin which'the wood and steel description set forth in detail certain means will work togetherand which will not open embodying my invention, such means conupunderany normal conditions of service, 30 stituting, however, but a few of the various including reasonable excess 'loa'dingy One v forms in which the principle of the invention way in which I; have provided such, a joint is may be illustrated' e by the means now to be described' In aid annexed drawing: I Ahol'e ,5, Figure6,is punched OI drilled Figure 1 is a broken side elevation of a in the leg 30f the angle 2. A screw 6, Fig: 'completesfioor joist in which one type of my ures fand 5, is then driven'through the hol improved composite member has been incor- 5 and'intoithe wood joist 1, thisdrive screw i porated; 6 having a pointedend 6 and beingof a Figures 2 and 3 are transverse vertical diameter somewhat larger than the hole 5 40 sections, upon an enlarged scale, taken in and being ofa length so as toenter the wood, the planes indicated by the lines 2+2 and 1 to'a depth of about two-thirds of the thick-, 33,' respectively; ness ofjthe wood I'have ascertained that Figure 4 is a transverse vertical section, the best kind ofa screw for this purpose is upon a still larger scale, taken'in the plane a rolled thread screw which is driven into 45 I indicated by the line 44, 'Figure 1; the wood rather than screwed in with a screw Figure 5 is a fragmentary longitudinal driver, and which becomes the more tightly vertical section, takenin the planeindicated fixed the harder it is pounded in, andfwhich by the line 5-5, Figure 4; in factworms its way through the wood or Figure 6 is a section similar to Figure 4 turns of its own accord as it is pounded in.. but showing the condition of the wood and Thus, the screw is incorporatedwithin and metal elements forming this type of the comintermingled with thematerial; of thewood 9' joist, and not merely contained within a hole having smooth sides and formed by the driving of a smooth faced tooth, tang, or prong into the wood. In order to make of this drive screw 6 what is in efi'ecta solid, stifi' steel stud formed upon the angle 2 and sticking up in the wood, I weld the head of the screw to the outside surface of the leg 30f the angle 2, as illustrated by the welded area 7.

Figure 7 is an illustration of a type ofmy new composite member in which the wood element 1 is combined with and rigidly se-- cured to two metal angle members 2 which also are rigidly secured together by rivets 21.

In thef-orm of member shown in Figure 8, I have substituted a channel 16 for the anglemember 2 and have securedthis channel by its web to the wood member 1.

In Figure 9 I also show a channel 17 which is secured to the wood'member 1- by one of its flanges.

In Figure 10 is shown the use of aT-member 18 which is secured by both of its flanges to the woodmember 1.

Figures 11 and 12 illustrate the use of my composite member as a column, the metal member 20 of Figure 11 being a channel construction which is pressedsnugly around the vertical wood member 19 and crimpedintothe' fieotions, to carry an excess over their normal'loading over acomparatively long continuous period of time without further deflection, and to resume their original position when their loads are removed. The

value of the steel which is thus saved by the use of the wood strip 1 as a structuralpart of the member is more than the value of the wood thus used'and therefore the member as a whole is manufactured on a more economical basis than a steel member of the same characteristics, When used as a joist, the wood'element 1 also serves as a nailing strip to whichthe wood floor can be directly secured.

A very good exemplificationof the application of my improved composite member to a complete structural unit is shown inFigures 1, 2 and 3. The construction is that'of a truss joist of a well'knowngeneral type comprising upper and lower spacedchords connected by a reversely bent webmember, thus forming a central truss, the ends of the chords being brought into proximate close relation and integrated to form extended unit-end supporting and bearing members which can be cut to provide a spanning by the joist of an one of a reasonable range of spans. Speci cally this truss joist comprises, in addition to the composite upper chord. hereinbefore described, a lower metal chord 8 having its ends 9brought into close parallel relation, with the ends of the upper chord angle 2, these chord ends being rigidly securedtogether and integrated through the medium of end angles having vertical legs 10'weldedto the vertical legs 4 of the upper chordangle 2, and having horizontal leg portions 11 to which the ends 9 of the lower chord-8 are welded. A reversely bent metal webrod 12-is alternately welded, as indicated by the welded areas 14: and 15, to

the lower chord-8 and the upper angle 2, throughout the more widely spaced relation of this chord 8 and angle 2, and the upwardly bent endportions 13 of the web-member- 12 weldedto the vertical legs 10 of the end angle members, all to form the complete unit shownin Figure 1. In this truss joists construction, the metal angle 2 running lengthwise of the joist serves thus as a means for securely attaching ,theweb member 12 to the composite upper chord.

Vhat I clalm is:

In a truss structure, an upper chord composed o'f'a woodsection and a. metal structuralmember secured together longitudinal- 1y by a series of driven screw-threaded fasteners the heads of which are welded to said metal member.

Signed by me this 15th day of November,

STANLE Y MACOMBER. 

